Index: trunk/test/unit/org/openstreetmap/josm/actions/mapmode/ImproveWayAccuracyActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/actions/mapmode/ImproveWayAccuracyActionTest.java	(revision 18961)
+++ trunk/test/unit/org/openstreetmap/josm/actions/mapmode/ImproveWayAccuracyActionTest.java	(revision 18963)
@@ -2,23 +2,76 @@
 package org.openstreetmap.josm.actions.mapmode;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.event.MouseEvent;
+import java.awt.image.BufferedImage;
+
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
 import org.openstreetmap.josm.TestUtils;
 import org.openstreetmap.josm.actions.mapmode.ImproveWayAccuracyAction.State;
+import org.openstreetmap.josm.data.Bounds;
+import org.openstreetmap.josm.data.coor.ILatLon;
+import org.openstreetmap.josm.data.coor.LatLon;
 import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.Way;
 import org.openstreetmap.josm.gui.MainApplication;
 import org.openstreetmap.josm.gui.MapFrame;
+import org.openstreetmap.josm.gui.MapView;
 import org.openstreetmap.josm.gui.layer.OsmDataLayer;
+import org.openstreetmap.josm.gui.util.GuiHelper;
 import org.openstreetmap.josm.testutils.annotations.Main;
 import org.openstreetmap.josm.testutils.annotations.Projection;
+import org.openstreetmap.josm.testutils.mockers.WindowlessMapViewStateMocker;
+import org.openstreetmap.josm.testutils.mockers.WindowlessNavigatableComponentMocker;
+
+import mockit.Mock;
 
 /**
  * Unit tests for class {@link ImproveWayAccuracyAction}.
  */
-@Main
 @Projection
 class ImproveWayAccuracyActionTest {
+    @RegisterExtension
+    Main.MainExtension mainExtension = new Main.MainExtension().setMapViewMocker(SizedWindowlessMapViewStateMocker::new)
+            .setNavigableComponentMocker(SizedWindowlessNavigatableComponentMocker::new);
+
+    private static final int WIDTH = 800;
+    private static final int HEIGHT = 600;
+    private static class SizedWindowlessMapViewStateMocker extends WindowlessMapViewStateMocker {
+        @Mock
+        public int getWidth() {
+            return WIDTH;
+        }
+
+        @Mock
+        public int getHeight() {
+            return HEIGHT;
+        }
+    }
+
+    private static class SizedWindowlessNavigatableComponentMocker extends WindowlessNavigatableComponentMocker {
+        @Mock
+        public int getWidth() {
+            return WIDTH;
+        }
+
+        @Mock
+        public int getHeight() {
+            return HEIGHT;
+        }
+    }
+
+    private static MouseEvent generateEvent(MapView mapView, ILatLon location) {
+        final Point p = mapView.getPoint(location);
+        return new MouseEvent(mapView, 0, 0, 0, p.x, p.y, p.x, p.y, 1, false, MouseEvent.BUTTON1);
+    }
+
     /**
      * Unit test of {@link ImproveWayAccuracyAction#enterMode} and {@link ImproveWayAccuracyAction#exitMode}.
@@ -45,5 +98,57 @@
     @Test
     void testEnumState() {
-        TestUtils.superficialEnumCodeCoverage(State.class);
+        assertDoesNotThrow(() -> TestUtils.superficialEnumCodeCoverage(State.class));
+    }
+
+    @Test
+    void testNonRegression23444() {
+        final DataSet dataSet = new DataSet();
+        final OsmDataLayer layer = new OsmDataLayer(dataSet, "ImproveWayAccuracyActionT", null);
+        MainApplication.getLayerManager().addLayer(layer);
+        final ImproveWayAccuracyAction mapMode = new ImproveWayAccuracyAction();
+        final MapFrame map = MainApplication.getMap();
+        assertTrue(map.selectMapMode(mapMode));
+        assertEquals(mapMode, map.mapMode);
+        final Way testWay = TestUtils.newWay("", new Node(1, 1), new Node(2, 1),
+                new Node(3), new Node(4, 1), new Node(5, 1));
+        testWay.firstNode().setCoor(new LatLon(0, 0));
+        testWay.lastNode().setCoor(new LatLon(0.001, 0.001));
+        testWay.getNode(1).setCoor(new LatLon(0.0001, 0.0001));
+        testWay.getNode(3).setCoor(new LatLon(0.0009, 0.0009));
+        dataSet.addPrimitiveRecursive(testWay);
+        assertFalse(testWay.getNode(2).isLatLonKnown(), "The second node should not have valid coordinates");
+        final Graphics2D g2d = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB).createGraphics();
+        g2d.setClip(0, 0, WIDTH, HEIGHT);
+        try {
+            // If this fails, something else is wrong
+            assertDoesNotThrow(() -> map.mapView.paint(g2d), "The mapview should be able to handle a null coordinate node");
+            // Ensure that the test way is selected (and use the methods from the action to do so)
+            GuiHelper.runInEDTAndWaitWithException(() -> {
+                map.mapView.zoomTo(new Bounds(0, 0, 0.001, 0.001));
+                // Get the target way selected (note: not selected in dataset -- use mapMode.mapReleased for that)
+                mapMode.mouseMoved(generateEvent(map.mapView, testWay.getNode(1)));
+            });
+            // mouseMoved shouldn't cause the way to get selected
+            assertFalse(dataSet.getAllSelected().contains(testWay));
+
+            // Now check painting (where the problem should occur; the mapMode.paint call should be called as part of the map.mapView.paint call)
+            assertDoesNotThrow(() -> map.mapView.paint(g2d));
+            assertDoesNotThrow(() -> mapMode.paint(g2d, map.mapView, new Bounds(0, 0, 0.001, 0.001)));
+
+            // Finally, check painting during selection
+            GuiHelper.runInEDTAndWaitWithException(() -> {
+                // Set the way as selected
+                mapMode.mouseReleased(generateEvent(map.mapView, new LatLon(0.0001, 0.0001)));
+                // Set the mouse location (unset in mouseReleased call)
+                mapMode.mouseMoved(generateEvent(map.mapView, new LatLon(0.0001, 0.0001)));
+            });
+            // The way shouldn't be selected, since it isn't usable for the improve way tool
+            assertFalse(dataSet.getAllSelected().contains(testWay));
+            // Now check painting again (just in case)
+            assertDoesNotThrow(() -> map.paint(g2d));
+            assertDoesNotThrow(() -> mapMode.paint(g2d, map.mapView, new Bounds(0, 0, 0.001, 0.001)));
+        } finally {
+            g2d.dispose();
+        }
     }
 }
